Methyl-CpG binding protein MBD2 is implicated in methylation-mediated suppression of miR-373 in hilar cholangiocarcinoma
Methyl-CpG binding protein MBD2 is implicated in methylation-mediated suppression of miR-373 in hilar cholangiocarcinoma
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甲基-CpG 结合蛋白 MBD2 参与甲基化介导的肝门部胆管癌中 miR-373 的抑制
DOI：
10.3892/or.2010.1089
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发表时间：
2011-02-01
期刊：
影响因子：
4.2
通讯作者：
Zou, Shengquan
中科院分区：
文献类型：
--
作者：
Chen, Yongjun;Gao, Wei;Zou, Shengquan
miRNAs的异常表达与显示组织和临床特征特异性模式的特定癌症相关。一些携带或嵌入CpG岛的miRNA基因经历甲基化介导的沉默。MBP，甲基CpG结合蛋白，通过结合甲基化CpG二核苷酸抑制转录。据报道，miR-373的表达在恶性胆管细胞系中受到抑制。生物信息学预测显示，miR-373的转录起始位点（TSS）位于一个402 bp的典型CpG岛上，含有26个CpG二核苷酸。本研究旨在探讨miR-373基因在肝门部胆管癌中的表观遗传调控。Taq Man microRNA检测显示miR-373的下调与肝门部胆管癌细胞分化差、临床分期晚、总生存期和无病生存期短密切相关。甲基化分析显示启动子相关的CpG岛是高甲基化的，这与miR-373的抑制一致。染色质免疫沉淀（ChIP）分析表明，miR-373的下调是由于MBD 2选择性募集到甲基化的CpG岛。相反，通过使用特异性siRNA敲低MBD 2促进miR-373的表达。通过5-aza-CdR和阿司他丁A（TSA）的药理学诱导重新激活miR-373导致MBD 2在CpG岛区域的富集减少。外源MBD 2在稳定表达pGL 4-m373-prom的稳定QBC（939）细胞中的增强表达诱导MBD 2的增强募集。我们的研究结果表明，miR-373是一个甲基化介导的基因和MBD 2在甲基化介导的抑制miR-373的暗示在肝门胆管癌的肿瘤发生和发展中起着重要作用。
Aberrant expression of miRNAs is associated with particular cancers showing tissue- and clinical-feature-specificity patterns. Some miRNA genes harboring or being embedded in CpG islands undergo methylation mediated silencing. MBP, methyl CpG binding protein, suppresses transcription through binding to methylated CpG dinucleotides. Expression of miR-373 has been reported to be suppressed in malignant bile duct cell lines. Bioinformatic prediction reveals that the transcription start site (TSS) of miR-373 is implanted in a 402 bp canonical CpG island containing 26 CpG dinucleotides. In this study, we aim to determine the epigenetic regulation of miR-373 gene in hilar cholangio-carcinoma. Taq Man microRNA assay shows that down-regulation of miR-373 is closely associated with poor cell differentiation, advanced clinical stage and shorter overall and disease-free survival in hilar cholangiocarcinomas. Methylation analysis shows that the promoter-associated CpG island is hypermethylated which is consistent with the inhibition of miR-373. Chromatin immunoprecipitation (ChIP) assay indicates that down-regulation of miR-373 resultes from the selective recruitment of MBD2 to methylated CpG islands. In contrast, MBD2 knock-down by use of a specific siRNA promoted the expression of miR-373. Reactivation of miR-373 by pharmacologic induction of 5-aza-CdR and trichostatin A (TSA) led to decreased enrichment of MBD2 at CpG island regions. Enhanced expression of exogenous MBD2 in stable QBC(939) cells which stably express pGL4-m373-prom induces strengthened recruitment of MBD2. Our findings suggest that miR-373 is a methylation-mediated gene and the implication of MBD2 in methylation-mediated suppression of miR-373 plays an important role in tumourigenesis and development in hilar cholangiocarcinoma.